It doesn't meet the poster's needs, but Simplenote is still a thing for people who want text-only notes, Markdown, and easy access to plain text files. It got

It doesn't meet the poster's needs, but Simplenote is still a thing for people who want text-only notes, Markdown, and easy access to plain text files. It got acquired by Automattic a few years back. https://simplenote.com/ https://simplenote.com/